Bronchopulmonary dysplasia (BPD) is a common form of lung injury that can be triggered by premature birth and the unavoidable exposures to treatments regularly used for premature infants,including mechanical ventilation and oxygen as well as conditions that occur frequently among premature infants including infection. Almost all infants who are born prematurely are exposed to either mechanical ventilation, extra oxygen, and many will develop at least one infection; however, not all premature infants will develop BPD. There is currently no way to identify those infants who are at risk for developing BPD, nor are there prognostic or diagnostic tests to determine the severity of lung disease in the first year after discharge from the hospital.